Thanks for the tip about --user-data-dir. BTW if you set that option to an empty directory, Chrome will populate it with new default settings, creating a new profile from scratch rather than basing it on an existing one.
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intuitedMar 6 '11 at 15:52

Just install two copies of Chrome (for example the regular version and the canary version). Use one for one account and the other for the other. Don't know if it this can be done on windows, it certainly works on the Mac. BTW use the regular and the canary version. They have different icons.

"Install two copies" - Do you mean download and install the binaries to two different locations? That seems inefficient, especially considering, as described in the other answer, you can choose which profile directory Chrome will use.
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IQAndreasJun 21 '14 at 9:05